It is known a method for ultrasonic measurement of flow velocity based on simultaneous operation of two sync rings in one electroacoustical channel one of which operates downstream, the other—upstream the flow (see USSR Author Certificate No 802709, Int. Cl. G01F1/66, 1981).
The known method does not provide, however, a sufficient accuracy of measurement of the flow velocity on base of which it is possible to appreciate the flow of liquid and/or gaseous medium.
In respect of a technical essence the closest prior art to the proposed method is an ultrasonic frequency-pulse method for measurement of the flow consisting in formation in one measuring channel of two sync rings switching in a radiation of ultrasonic oscillations downstream relative to the flow of the medium to be measured downstream and upstream thereof, reception of the oscillations passed through the medium and conversion of them into an electrical signal, herewith electrical signals in each sinc ring are transmitted via a communications line, measurement of frequency of signals following in each sync ring, and determination of a value of the flow is made according to a difference in measured frequencies (see Russian patent No 2104498, Int. Cl. G01F1/66, of Feb. 16, 1993).
The known method does not provide, however, sufficient accuracy of measurement of medium flow, since the measurement is performed only according to results of analysis of electrical signals converted from ultrasonic oscillations passed directly from one transducer to other one that reduces functionality of the method and does not provide determination of the flow velocity in different points of a pipe cross section.
It is known an ultrasonic frequency-pulse flowmeter comprising a flow transducer made in form of two electroacoustic transducers mounted on a measuring section of a pipeline and coupled with an electronic block via a communications line, as well as asynchronous switches mounted in parallel to input and output of a communications line (see Russian patent No 2104498, Int. Cl. G01F1/66, of Feb. 16, 1993).
The known apparatus does not provide, however, a sufficient accuracy of measurement of the flow of medium since it does not provide for determination of the flow velocity in different points of a pipe cross section.
In respect of the technical essence the closest to the proposed apparatus prior art is an ultrasonic flowmeter comprising first and second piezoelectric emitters mounted on a measuring section of the pipeline at an angle to its axis, a power amplifier being coupled via a first frequency multiplier with a second piezoelectric emitter, a continuous wave oscillator, two filters, a first phase shifter coupled with first input of a phase-meter, a second frequency multiplier coupled with a second input of the phase-meter output of which is coupled with an indicator, first an second piezoelectric receivers, first and second limiting amplifiers, a second phase shifter, a modulator and a square-wave generator (see USSR Author Certificate No 1599659, Int. Cl. G01F1/66, of Aug. 22, 1987).
However, and this known apparatus does not provide high accuracy of the measurement of flow of substance since the measurement is made only on one way of passage of ultrasonic oscillations in a measuring section of a pipeline and is not made on other ways. Therefore is not provided the measurement of orthographic epure of flow velocity along a pipe cross section.
Moreover, in the known technical solutions axes of the directional diagrams of ultrasonic transducers are not perpendicular to the longitudinal axis of pipeline, and external radiating surfaces are not combined with an inner surface of the pipeline.
This results in formation of hollows which distort a profile of the flow and collect pollutions.